A critical role for dendritic cells in the evolution of IL-1β-mediated murine airway disease.

Department of Pathology, University of California, San Francisco, San Francisco, CA 94110; and.

2

Department of Medicine, University of California, San Francisco, San Francisco, CA 94110.

3

Department of Pathology, University of California, San Francisco, San Francisco, CA 94110; and stephen.nishimura@ucsf.edu.

Abstract

Chronic airway inflammation and fibrosis, known as airway remodeling, are defining features of chronic obstructive pulmonary disease and are refractory to current treatments. How and whether chronic inflammation contributes to airway fibrosis remain controversial. In this study, we use a model of chronic obstructive pulmonary disease airway disease utilizing adenoviral delivery of IL-1β to determine that adaptive T cell immunity is required for airway remodeling because mice deficient in α/β T cells (tcra(-/-)) are protected. Dendritic cells (DCs) accumulate around chronic obstructive pulmonary disease airways and are critical to prime adaptive immunity, but they have not been shown to directly influence airway remodeling. We show that DC depletion or deficiency in the crucial DC chemokine receptor ccr6 both protect from adenoviral IL-1β-induced airway adaptive T cell immune responses and fibrosis in mice. These results provide evidence that chronic airway inflammation, mediated by accumulation of α/β T cells and driven by DCs, is critical to airway fibrosis.

Percoll enriched lung immune cell populations were analyzed by multicolor flow cytometry multicolor staining of lung immune cell populations from wild-type (WT), untreated (A, D), or compound transgenic (CD11c-DTR;CD11c-YFP) mice (B, C, E, F) treated with IT- Ad-IL-1β Five days after infection, CD11c-DTR;CD11c-YFP mice were treated with PBS or diphtheria toxin (DT). At day seven, at the peak of IL-1β expression, mice were euthanized and lung cell suspensions stained for CD11c, CD11b, MHCII, F480, Ly6c and Gr1. Staining for CD11c on the y-axis and YFP fluorescence on the x-axis are indicated for lung DC populations (A–C) and alveolar macrophages (D–F). The gates used to determine depletion of DCs or AMs are shown and the gating strategy shown in .

DC airway localization is increased by IT-Ad-IL-1β treatment of CD11c-DTR;CD11c-YFP mice and completely blocked by DT

CD11c-DTR;CD11c-YFP mice were treated with Ad-LacZ (A, C) intratracheal (IT)-Ad-IL-1β (B, D). Five days after infection, CD11c-DTR;CD11c-YFP mice were treated with PBS (A, B) or diphtheria toxin (DT) (C, D). At day seven, at the peak of IL-1β expression, mice were euthanized and vibratome living lung sections analyzed using 2-photon microscopy. The YFP positive cells are shown as yellow cells against a Hoechst (blue) counterstained background. The number of DCs within 100 µm (E), or outside of 100 µm (F) from the airway basement membrane was assessed using automated cell analysis (IMARIS). Bar = 100 µm.

Representative histologic images from CD11c-DTR mice treated with either Ad-LacZ (A, D) or Ad-IL-1β (B, C, E, F). 5 days after adenoviral administration mice were treated with PBS (A–C), or DT (4 ng/g body weight, D–F) I.P. and mice were euthanized on day 9. Bar=100 µm. Airway morphometry of H&E stained sections was performed to determine the area of inflammation around the airways (A, B, D, E, G) or the extent of fibrosis around the airway wall (C, F, H), as determined by trichrome staining and airway morphometry as described by Hogg, et al () and adapted to mice in Kitamura, et al (). Open bars = PBS; closed bars = DT. A=Airway lumen. Error bars are S.E.M; ***p<0.001 as determined by ANOVA and Bonferroni’s post-test.